Buckwheat is very good for the soil when worked back in, but can be invasive

Finding that it sure is LOL . My first planting of buckwheat I left go to seed , mowed and till along with sorghum grass , I mowed and tilled before any flowers and after the first rainfall it looks like I had broadcasted buckwheat again !!! I ran the tiller though it the other day trying to kill what sprouted and hoping that more will germinate so I can kill that before planting the winter rye . I hope if any germinates it will die before flowering , we'll see